Performance evaluation of a large capacity 3-level IEGT inverter

Many large capacity motor drive equipments have been used in steel plants for many years. High-efficiency motor drive equipments are required in this industrial field. The appearance of the IGBT (Insulated Gate Bipolar Transistor) or IEGT (Injection Enhanced Gate Transistor) made the large PWM (Pulse Width Modulation) drive system practical. Normally, the voltage source type such as IGBT or IEGT inverter has low harmonics and high-efficiency. So, it has spread widely now. However, the cycloconverter is still operating now and it has relatively low power factor and high-harmonics compared with IGBT/IEGT inverter. So, the demand of IGBT/IEGT inverter is increasing to replace the conventional cycloconverter. The IEGT inverter has excellent performance characteristics that make it suitable for steel plants main drives and many other high performance applications. In this study, it is introduced the development of a large-capacity and high-efficiency 3-level IEGT inverter for steel plants application. 1 bank of this inverter has a capacity of 9MVA, so by connecting 4 banks in parallel it is possible to obtain 36MVA rating. This paper also reports the features of the IEGT inverter with the results of a full power test obtained by the 3-level IEGT inverter which confirms 9MVA rated output capacity and 1MVA/m³ power density.